The long-term objectives of this research are: the improvement of the basic understanding of ventricular and muscle function in healthy and dysfunctional hearts, and the evaluation of a potential approach to rapid and accurate clinical assessment of ventricular function through development and application of an analytic model of the cardiac function. The mathematical model of the human LV developed previously has been applied to the simulation of muscle performance in twenty patients to date. The results of these simulations indicate that muscle fiber stress, power and work per unit volume are much more sensitive to ventricular dysfunction than the more commonly used parameter of maximum contractile element velocity. A major objective of the proposed research is to establish the validity of these initial results in a patient population large enough for statistically meaningful conclusions. The approach taken is to use a mathematical model of muscle function in the LV to simulate the performance of a specific patient's ventricle. The model uses dimensional and pressure data obtained during routine cardiac catheterization and biplane cineangiography to attain a specific simulation. As a result of the simulation, numerical predictions of muscle fiber stress, contractile element velocity, and length and contractile element power and work are obtained at prescribed locations in the LV wall at 10 msec. intervals through systole. In the results obtained to date the predicted values of stress, power and work have been more sensitive indicators of myocardial contractility than contractile element velocity. The primary goal of the research is to obtain a statistically significant data base so that the results of any given patient simulation can be critically viewed with a known level of confidence. This goal is to be achieved by applying the mathematical model of the LV to the simulation of a large number of LV's using data from both biplane and single plane angiography.